The double bass (or contrabass) is the largest and lowest pitched instrument in the bowed string family. The double bass derived from the violone, an earlier form of bass string instrument (although the term violone is an imprecise one used for various instruments including the bass and double bass viol, and even as a synonym for the violincello). The double bass originally had three strings but now has four usually tuned to E, A, D, & G and has a range of nearly three octaves. The pitch of the strings on a double bass are also an octave lower than its written notation.
The double bass has a sightly different look to the other members of the string family, with sloping shoulders tapering into the neck (a remnant of its ancestor the viol), and cogwheel tuning pegs instead of the friction based ones found on the other string instruments. The double bass stands on a adjustable peg and is supported by the body and left knee of the player. The player also sometimes sits on a high stool while playing. Double basses come in different sizes, the three-quarter size being preferred for general orchestral use as it is more manageable than the full-sized bass.
Originally, the use of the double bass in the orchestra was typically confined to doubling the cello part but eventually bass parts became more independent and even some concertos for double bass and orchestra have been written, including by Joseph Haydn (the score of which is now lost), Giovanni Bottesini, and more recently by the brilliant Swedish composer Fredrik Högberg.
Although the double bass is mainly an orchestral instrument, it may be better recognised as an instrument in jazz ensembles where it is play mostly ‘pizzicato’ (plucking with the fingers).